1. Field of the Invention
This invention relates to supports and connecting apparatus for high pressure liquid chromatography (HPLC) columns and more particularly to a column support and connector apparatus adapted to facilitate the rapid mounting, release and interchange of columns in the apparatus.
2. Description of the Prior Art
The prior art related to this invention is believed to reside in Class 210, sub-class 198.
A preliminary patentability search through this area has indicated the existence of the following U.S. Pat. Nos. 3,266,554; 3,878,099; 3,531,919; 4,079,009; 4,288,007; 4,650,595; 4,440,550; 4,478,715.
While all of the patents noted above relate to chromatography devices, perhaps the most pertinent of the patents is U.S. Pat. No. 4,478,715 which discloses a column retainer and connector to other fluid flow members involving a split collet and collet nut for tightening onto the outside of a chromatography column. However, such a device is hardly applicable to the HPLC columns considered herein as these have specially designed end-fittings or column-connection unions applied to the highly-polished stainless steel tubes at the time the columns are packed with appropriate chromatographic packing materials.
A major problem in working with conventional HPLC columns has been that columns made by different manufacturers have different end-fittings, with different depths of ferrule seats and tube stops, thereby imposing a severe restriction on the user with respect to the variety of columns usefully accessible, it being generally not possible to change the style of end-fitting on a prepacked column. Accordingly, it is one of the objects of the present invention to provide an HPLC mounting station or apparatus which has universal sealing applicability and which can accommodate columns from different manufacturers.
A further object of the invention is to minimize or reduce to zero the fluid dead volume of the connections between the station and HPLC columns, the fluid dead volume being the fluid space between the input end of the fluid feed line, which has a generally micro-sized bore, and the surface of the packing materials in the HPLC column. This object is of particular significance since column end-fittings from different manufacturers may be either of the `low dead volume` (LDV) or `zero dead volume` (ZDV) design.
The high pressures employed in HPLC systems require that particular attention be given to the seals between the various components of the system. Accordingly, another object of the invention is to provide pressure seals between the station and HPLC columns which neither leak externally, nor permit internal leakage between components of the fluid system itself.
Conventional practice of liquid chromatography utilizing conventional HPLC columns, for best performance, dictates that each column should have a custom-made connecting tube. In general, to effect such custom-made connections, it is standard practice to have available an assortment of nuts, ferrules, and connecting tubes. This is particularly true where a conventional precolumn or in-line filter is used. Accordingly, it is another object of the invention to provide an apparatus that eliminates the need of all these extra nuts, ferrules and the tools required for their connection.
Still another object of the invention is the provision of a HPLC column mounting apparatus or station which provides for the convenient mounting of a sample injector as close to the column inlet as is feasible, to reduce to a minimum the delay, dilution, and detrimental band spreading effects due to mixing associated with introducing a sample onto the HPLC column.
Conventional HPLC columns are expensive components, and are susceptible to being contaminated and rendered useless after only limited use if care is not used regarding the purity of the solvent or fluid phase caused to pass through the column. It is conventional practice, to lessen the risk of such contamination, to utilize a precolumn or in-line filter to initially separate from the solvent any contaminants or impurities. Such filters cost much less than the columns, and significantly increase the life of the column, and assist in maintaining the efficiency of the column. The major problem encountered with use of such precolumn or in-line filters is the necessity of the additional liquid tight connections, the need to use tools to make those connections, and the expenditure of considerable time to effect the connections. Accordingly, it is a still further object of the invention to provide an apparatus for supporting and sealingly connecting a HPLC column and a precolumn or in-line filter in series with each other without the use of tools of any kind and solely by the application of axially directed mechanical pressure on the filter and column.
The invention possesses other objects and features of advantage, some of which, with the foregoing, will be apparent from the following description and the drawings. It is to be understood however that the invention is not limited to the embodiment illustrated and described, since it may be embodied in various forms within the scope of the appended claims.